Proposal: Sameness operators

Mark Thornton mthornton at
Thu Apr 2 05:48:15 PDT 2009

Tom Hawtin wrote:
> Reinier Zwitserloot wrote:
>> Why can't we use compareTo and equals?
>   * compareTo may well be unreasonably inefficient.
>   * equals handles nulls (asymmetrically), compareTo does not
>   * equals does test-and-cast (event for generic types - urgh), 
> compareTo uses generics
>   * equals does not throw ClassCastException, compareTo does (but 
> probably shouldn't with generics)
> Therefore, new methods please. I'm sure you are aware the whole subject 
> of operator overloading in general is a minefield.
a.compareTo(b) == 0 and a.equals(b) are not always the same, sometimes 
for very good reasons. I seem to remember that there is at least one 
such class in the Java platform.

Mark Thornton

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